Conventional practice for dividing a stream of liquid into predetermined portions is based on the principle of orifice flow or the overflow over a notched weir.
In an orifice flow splitter, equal division of the liquid is achieved by flow through orifices of equal size. The flow rate can be varied by changing the pressure of the liquid upstream of the orifice.
If division of a liquid stream is to be accomplished substantially in the absence of pressure, that is by gravity flow, a notched weir is commonly used. Obviously, such a weir has to be perfectly level to function satisfactorily.
In certain applications of flow distributors such as in the fertilization of soil with anhydrous ammonia by the nonpressure method disclosed in U.S. Pat. No. 3,978,681, incorporated herein by reference, uniform distribution of a liquid through a multitude of hoses has to be accomplished by gravity flow.
The uniform distribution is achieved by the use of a distributor such as the one described in U.S. Pat. Application Ser. No. 786,302, filed Apr. 11, 1977, incorporated herein by reference. Typical maximum outlet connections range up to approximately 24 per distributor. However, it is desirable for larger field equipment to have more than 24 outlets to cover a broader width or to be able to place the application points more closely. Distributors with more than 24 outlets are impractical due to the excessive width required to accommodate the large number of hose connections.
To provide more than 24 outlets, two or more distributors have to be used. This arrangement not only provides a sufficiently large number of total outlets, but avoids excessive lengths of application hoses, as would be the case with a single large distributor. In fact, the total length of application hoses required for a given size of field equipment is less with two small distributors than with one large one.
However, the use of two distributors requires division of the feed stream into two equal portions. Therefore a device is necessary which is able to split a gravity-flow stream into equal portions over a wide range of flow rates.
Because of the nature of the application method, use of pressure is undesirable and detrimental. Furthermore, the apparatus for dividing a liquid stream has to be simple, compact, and rugged, preferably without moving parts, and has to function properly at various degrees of tilt since it is mounted on equipment being moved across fields which are not necessarily level.
For this reason, conventional flow splitters are not suited to meet the need of field application equipment when liquids are to be applied by gravity flow.